Synthesis for photographic sensitizing dyes



United States Patent 3,483,195 SYNTHESIS FOR PHOTOGRAPHIC SENSITIZING DYES Roy A. J eifreys, Wealdstone, Harrow, Middlesex, England,

assignor to Eastman Kodak Company, Rochester, N .Y.,

a corporation of New Jersey No Drawing. Filed Oct. 9, 1963, Ser. No. 314,864 Int. Cl. C09b 23/00; G03c 1/12 US. Cl. 260240.4 11 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a novel method for prepara tion of sensitizing dyes of the styryl class, the hemicyanine class, merocyanine class and complex dye class from N,N-dimethylisopropylimmonium perchlorate by its reaction with an intermediate selected from the class consisting of an amino substituted aldehyde, a 2-alkylthioheterocyclic quaternary salt, a Z-acetanilidovinyl heterocyclic quaternary salt, an alkoxymethylene derivative of ketomethylene heterocyclic compound and ethylisoformanilide.

Styryl, hemicyanine, merocyanine and complex dyes are known in the art. These dyes are usually made by condensing a suitable cyclammonium quaternary salt with with an appropriate intermediate under suitable conditions. For example the synthesis of certain styryl dyes is described by Brooker et al. US. Patent 2,494,032 issued 1 an. 10, 1950, the synthesis of certain hemicyanine dyes is described by White US. Patent 2,369,509 issued Feb. 13, 1945, and the synthesis of certain merocyanines is described by Aubert and Knott US. Patent 2,652,397 issued Sept. 15, 1953. These reactions are usually conducted in a suitable solvent in the presence of a basic condensing agent and at a temperature between room temperature and the reflux temperature of the solvent in the reaction mixture.

New methods for preparing sensitizing dyes are desired. It is therefor an object of my invention to provide a novel method for preparing sensitizing dyes of the styryl class, the hemicyanine class, merocyanine class and complex dye class derived from N,N-dimethylisopropylimmonium perchlorate.

Another object is to provide a process of making dyes comprising treating N,N-dimethylisopropylimmonium perchlorate with an intermediate selected from the class consisting of an amino substituted aldehyde, a 2-alkylthioheterocyclic quaternary salt, a Z-acetanilidovinyl heterocyclic quaternary salt, an alkoxymethylene derivative of a ketomethylene heterocyclic compound and ethylisoformanilide.

Another object is to provide sensitizing dyes made by my process. Another object is to provide photographic silver halide emulsions sensitized with my dyes.

Still other objects will become evident from a consideration of the following specification and claims.

These and other objects are accomplished according to my invention by heating a mixture of (l) a compound having the formula:

wherein R and R each represents alkyl groups, e.g., methyl, ethyl, propyl, butyl, etc., and (2) an intermediate, e.g., an amino substituted aldehyde, a 2-alkylthioheterocyclic quaternary salt, a 2-acetanilidovinyl heterocyclic quaternary salt, an alkoxymethylene derivative of ketomethylene heterocyclic compounds and ethylisoformanilide. Merocyanines and hemicyanines can also be made to advantage by heating a mixture of (1) a compound having the formula:

C H NHOH=OHC=N(CI-I:)2 0104 in which R is as defined previously, and acetic anhydride with (2) an intermediate, e.g., a heterocyclic quaternary salt with a reactive methyl group, or a ketomethylene heterocyclic compound. In place of the compound of Formula II and acetic anhydride in this reaction one can use a compound of formula: HA C I-I NCII=OHC=%(CH3)2 c104 in which R is as defined previously. Compounds of Formula IIA are prepared by refluxing the appropriate compound of Formula II with acetic anhydride.

These reactions of my invention are carried out advantageously in a suitable inert organic solvent, and at a temperature between room temperature and the reflux temperature of the reaction mixture. It is advantageous to conduct the reactions in the presence of a basic condensing agent.

The inert solvents used to advantage include ethanol, propanol, isopropanol, 1,4-dioxane, pyridine, quinoline, etc. The basic condensing agents include organic tertiary amines, such as the trialkylamines e.g., triethylamine, tripropylamine, triisopropylamine, tributylamine, etc., the N,N-dialkylanilines, e.g., N,N-dimethylaniline, N,N-di- Inethylaniline, etc., the N-alkylpiperidines, e.g., N-methylpiperidine, N-ethylpiperidine, etc.

The amino substituted aldehydes used to advantage in my synthesis for the preparation of styryl dyes, includes the aldehydes represented by the formula:

III R2 \N O m/ wherein R and R each represent the same or a different group, such as, the hydrogen atom, an alkyl group, e.g., methyl, ethyl, propyl, butyl, amyl, 2-chloroethyl, Z-cyanoethyl, Z-hydroxyethyl, benzyl, etc., an aryl group, e.g., phenyl, p-chlorophenyl, p-tolyl, p-ethylphenyl, etc.

The 2-alkylthio, Z-acetanilidovinyl heterocyclic quaternary salts, and reactive methyl heterocyclic quaternary salts used to advantage in my synthesis for making hemicyanine dyes includes the quaternary salts represented by the formulae:

wherein R represents an alkyl group, e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, allyl (i.e., vinylmethyl), ethoxycarbonylmethyl, fi-hydroxyethyl, ,8- acetoxyethyl, sulfobutyl, etc.; R represents an alkyl group, e.g., methyl, ethyl, etc., an aryl group, e.g., phenyl, p-chlorophenyl, p-tolyl, etc.; Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus containing from five to six atoms in the heterocyclic ring,

such as those selected from the group consisting of the thiazole series [c.g. thi azole,

4-methylthiazole, 4-pheny1thiazole, S-rnethylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4- Z-thienyl) thiazole,

etc.], those of the benzothiazole series (e.g. benzothiazole,

etc.), those of the naphthothiazole series (e.g.

a-naphthothiazole, B-naphthothiazole, 5-rnethoxy-fi-naphthothiazo1e, 5-ethoxy-B-naphthothiazole, 8-methoxy-a-naphthothiazole, 7-methoXy-u-naphthothiazole,

etc.), those of the thionaphtheno-7,6,4,S-thiazole series (e.g. 4-methoxythianaphtheno7,6',4,5-thioazole, etc.), those of the oxazole series (e.g. 4-methyloxazole, 5- methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4- ethyloxazole, 4,5-dimethyloxazole, 5-phenyloxazole, etc.), those of the benzoxazole series (e.g. benzoxazole,

S-chlorobenzoxazole,

5 methylbenzoxazole, S-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethyl'benzoxazole, 4,6-dimethylbenzoxazole, 5 -methoxybenzoxazole, S-ethoxybenzoxazole,

5 -chlorobenzoxazole, G-methoxybenzoxazole, S-hydroxybenzoxazole, 6-hydroxybenzoxazole,

etc.), those of the naphthoxazole series (e.g. rat-naphthoxazole, fi-naphthoxazole, etc.), those of the selenazole series (e.g. 4-methylselenazole, 4-phenylselenazole, etc.), those of the benzoselenazole series (e.g. benzoselenazole, S-chlorobenzoselenazole, 5-methoxybenzoselenazole, 5- hydroxybenzoselenazole, tetrahydrobenzoselenazole, etc.), those of the naphthoselenazole series (e.g. a-naphthoselenazole, B-nalphthoselenazole, etc.), those of the thiazoline series (e.g. thiazoline, 4-methylthiazoline, etc.), those of the 2-quinoline series (e.g. quinoline, S-methylquinoline, S-methylquinoline, 7-methylquinoline, 8- methylquinoline, 6-chloroquinoline, 8-ch1oroquinoline, 6- methoxyquinoline, -ethoxyquinoline, 6-hydroXyquinoline, S-hydroxyquinoline, etc.), those of the 4-quinoline series (e.g. quinoline, 6-methoxyquinoline, 7-methylquinoline, 8-methylquino1ine, etc.), those of the Usequinoline series (e.g. l-isoquinoline, 3,4-dihydro-1-isoquinoline, etc.), those of the 3-isoquino1ine series (e.g. 3-isoquin01ine, etc.), those of the 3,3-diaikyl-3H-indole series (e.g. 3,3-dimethyl-3H-indole, 3,3,5-trimethy1-3H- indole, 3,3,7-trimethyl-3H-indo1e, etc.), the pyridine series (e.g. pyridine, S-me'thylpyridine, etc.), etc., the 2-pyridine series (e.g., 2-pyridine, S-methyl-Z-pyridine, etc.), the 4-pyridine series (e.g., 4-pyridine, 5-methyl-4- pyridine, etc.); those of the imidazole series (e.g., imidazole, 1 ethyl 4phenylimidazole, 4,5-dimethylimidazole, etc.); the benzimidazole series (e.g., l-ethylbenzimidazole, l-phenyl-benzimidazole, etc.), and those of the naphthimidazole series (e.g., l-methyl-a-naphthiinidazole, (3 naphthimidazole, 5 methoxy-{i-naphthimidazole, etc.), and X represents an acid anion, such as chloride, bromide, iodide, perchlorate, sulfonate, thiocyanate, p-toluenesulfonate, benzenesulfonate, methylsulfate, ethylsulfate, etc.

The ketomethylene heterocyclic compounds used to advantage in my synthesis for making merocyanine dyes include the compounds represents by the formula:

wherein W represents the nonmetallic atoms necessary to complete a heterocyclic nucleus containing from five to six atoms in the heterocyclic ring, such as, those of the Z-pyrazolin-S-one series (e.g. 3-methyl-l-phenyl-Z-pyrazolin-S-one, 1 phenyl-Z-pyrazzolin-S-one, 1-(2-benzothiazolyl)-3-methyl 2 pyrazolin 5 one, etc.), those of the isoxazolin-S-one series (e.g. 3-phenyl-2-isoxazo1in-5-one, 3-methyl-2-isoxazolin-5-one, etc.), those of the 2-indo1inone series, (e.g. l-alkyl-Z-indolinone, etc.), those of the 2,4,6-triketohexahydropyrimidine series (erg. barbituric acid or Z-thiobarbituric acid as well as their l-alkyl (e.g. l-methyl, l-ethyl, l-propyl, l-heptyl, etc.), or 1,3-dialkyl (e.g. 1,3-dimethy1, 1,3-diethyl, 1,3-di-propy1, 1,3-diisopropyl, 1,3-dicyclohexyl, l,3-di(fl-methoxyethyl), etc.), or 1,3-diary1 [c.g. 1,3-diphenyl, l,3-di(p-chlorophenyl), 1,3- di(p-ethoxycarbonylphenyl), etc], or l-aryl (e.g. 1- phenyl, l-p-chlorophenyl, l-p-ethoxycarbonylpheny1, etc.) or l-alkyl-3-aryl (e.g. 1-ethyi-3-phenyl, 1-heptyl-3-phenyl, etc., derivatives), those of the rhodanine series (i.e. Z-thio- 2,4-thiazolidinedione series), such as rhodanone, 3-a1kylrhodanines (e.g. 3-ethylrhodanine, 3-allylrhodanine, etc.) or 3-arylrhodanines (e.g. 3-phenylrhodanine, etc.), etc., those of the 2(3H)-imidazo[1,2-a]pyridone series, those of the 5,7-dioXo-6,7-dihydro-5-thiazolo[3,2-a] pyrimidine series (e.g. 5,7-dioxo-3-phenyl-6,7-dihydro-S-thiazolo[3,2- a]pyrimidine etc), those of the thianaphthenone series (e.g. 3-(2H)-thianaphthenone, etc.), those of the 2-thio- 2,5-thiazolidinedione series (i.e. the 2-thio-2,5(3H, 4H)- thiazoledione series) (e.g. 3-ethyl-2-thio-2,S-thiazolidinedione, etc.), those of the 2,4-thiazo1idinedione series (e.g. 2,4-thiazolidinedione, 3 ethyl 2,4 thiazolidinedione, 3 phenyl 2,4 thiazolidinedione, 3-a-naphthyl-2,4-thiazoli dienedione, etc.), those of the thiazolidinone series (e.g. 4-thiazolidinone, 3-ethy1-4-thiazolidinone, 3-pheny1-4-thiazolidinone, 3-a-naphthyl-4-thiazolidinine, etc.), those of the 4-thiazolinone series (e.g. 2-ethylthio-4-thiazo1inone, 2-alkylphenylamino-4-thiazolinones, Z-diphenylamino 4 thiazolinone, etc.), those of the 2-imino-2,4-oxazolinone (i.e. pseudohydantoin) series, those of the S-imidazolinone series (e.g. 2-propy1thio-5-imidazolinone, etc.), etc. (especially a heterocyclic nucleus containing 5 atoms in the heterocyclic ring, 3 of said atoms being carbon atoms, 1 of said atoms being a nitrogen atom, and 1 of said atoms being selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom).

The derivatives of ketomethylene heterocyclic compounds used to advantage in my synthesis for making merocyanine dyes include the compounds represented by the formulae:

VII JV.

VIII -W- =oo=oH-NCu1 O=C-CH3 wherein W is as defined previously, and R represents an alkyl group, e.g., methyl, ethyl, propyl, butyl, amyl, benzyl (i.e. phenylmethyl), allyl, etc.

Intermediates having Formulas III, IV, V, VI, VII and VIII are well known in the art and are described in the literature and in numerous patents, and need not be described further here.

The merocyanine dyes made by my synthesis from rhodanine and similar thiones can be alkylated with an alkylester and condensed further to give complex dyes.

The dyes of my invention are used to advantage in manufacturing photographic silver halide emulsions, serving to alter the sensitivity thereof. The type of silver halide emulsions that are sensitized with my dyes include any of those prepared with hydrophilic colloids that are known to be satisfactory for dispersing silver halides, for example, emulsions comprising materials such as, gelatin, a1- bumin, agar-agar, gum arabic, alginic acid, etc., and hydrophilie synthetic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose ethers, partially hydrolyzed cellulose acetate, and the like.

In the preparation of photographic emulsions, my dyes are advantageously incorporated in the finished silver halide emulsion and should, of course, be uniformly distributed throughout the emulsion. The methods of incorporating dyes in emulsions are relatively simple and well known to those skilled in the art of emulsion making. For example, it is convenient to add the dyes from solutions in appropriate solvents, in which case the solvent selected should be completely free from any deleterious effect on the ultimate light-sensitive materials. Methanol, isopropanol pyridine, etc., alone or in admixtures, have proven satisfactory as solvents for the majority of my dyes.

The concentration of my dyes in the emulsion can be varied widely, i.e., from about 5 to about 100 mg. per liter of flowable emulsion. The specific concentration will vary according to the type of light-sensitive material in the emulsion and according to the effects desired. The suitable and most economical dye concentration for any given emulsion will be apparent to those skilled in the art upon making the tests and observations customarily used in the art of emulsion making.

To prepare a gelatino-silver halide emulsion sensitized with one of our new dyes, the following procedure is satisfactory: A quantity of the dye is dissolved in a suitable solvent and the volume of this solution containing from 5 to 100 mg. of dye is slowly added to about 1000 cc. of the gelatino-silver halide emulsion. With most of my dyes, 10 to 20 mg. of dye per liter of emulsion suflice to produce the maximum sensitizing effect with the ordinary gelatino-silver bromide (including bromoiodide and chlorobromide) emulsions. With fine grain emulsion, which include most of the ordinarily employed gelatinosilver chloride emulsions, somewhat larger concentrations of the dye may be necessary to secure optimum sensitizing eflect, while the preceding has dealt with gelatino emulsions, it will be understood that these remarks apply generally to any emulsions wherein part or all of the gelatin is replaced by another suitable hydrophilie colloid such as mentioned above.

The above statements are only illustrative and are not to be understood as limiting the invention in any sense, as it will be apparent that my dyes can be incorporated by other methods in many of the emulsions employed in the art. For instance, the dyes can be incorporated by bathing a plate or film upon which the emulsion has been coated, in the solution of the dye in an appropriate solvent.

The following typical examples will serve to further describe my invention, however, it is to be understood that my invention is not to be limited to these examples.

EXAMPLE 1.l-p-DIMETHYLAMINOPHENYL-3-DI- METHYLIMMONIUM-l-BUTENE PERCHLORATE p-Dimethylaminobenzaldehyde (3 g.) and N,N-dimethylisopropolyimmonium perchlorate (3.7 g.) in ethanol (12 cc.) with piperidine (2 drops), were refluxed together for A: hr. The solution was chilled, and the solid product filtered off, washed with water and ether, and recrystallized from methanol-ether as purple-brown prisms, M.P. 244 C.

The dye sensitized a silver chlorobromide emulsion from 480 my, to 660 m and a silver bromoiodide emulsion to 630 m with a peak at 580 mu.

EXAMPLE 2.-5- 3-DIMETHYLAMINOBUT-2-EN- YLIDENE)-S-ETHYLRHODANINE CzH N(|3O morn so G=CHOH= CH3 l-anilino-3-dimethylimmonium-Z-butene perchlorate (2.88 g.) and ethylrodanine (1.6 g.) with acetic anhydride (1.0 cc.) and triethylamine (2.8 cc.) in ethanol (15 cc.), were refluxed together for /2 hr. and the solution was chilled. The product was filtered off, washed with a little ethanol, and recrystallized from ethanol as bright orange leaflets, M.P. 189 C.

The dye sensitized a silver chloride emulsion from 450 me to 560 m with a peak at 530 m EXAMPLE 3 .5 (3 DIMETHYLAMINOBUT-Z-EN- YLIDENE) 3 ETHOXYCARBONYLMETHYL- RHODANINE 0211 0 0 O CH2N OO 3-ethoxycarbonylmethyl 5 ethoxymethylene-rhodanine (2.75 g.) and N,N-dimethylisopropylimmonium perchlorate (1.86 g.) with triethylamine (1.4 cc.) in ethanol 12 cc.) were refluxed for /2 hr. and the solution was chilled. The product was filtered off, washed with ethanol, and recrystallized from ethanol as orange leaflets, M.P. 162 C.

It sensitized a silver chlorobromide emulsion to 610 m with a peak at 550 mu, and a silver bromoiodide emulsion to 600 m, with a peak at 450 mp.

EXAMPLE 4.-2- Z-DIMETHYLAMINOPROPENYL) 3-ETHYLBENZOTHIAZOLIUM PERCHLORATE the.

tative dyes, such as Dye 2, and Dye 3 are further condensed to make complex dyes.

EXAMPLE 5 3 ETHYL 2 BENZOTHIAZOLE)- [5-(3-DIMETHYLAMINOBUT 2 ENYLIDENE)- 3 ETHYL 4 THIAZOLIDINONE1METHINCY- ANINE IODIDE The dye Example 2 (0.26 g.) and methyl p-toluenesulfonate (0.2 g.) were fused at 120 for 1 hr. 3-ethyl-2-methylbenzothiazolium iodide (0.31 g.) triethylamine (0.14 cc.) and ethanol cc.), were added and the solution was refluxed for minutes, and then chilled. The product was filtered oil, washed with ethanol, and recrystallized from ethanol-ether as dark green crystals, M.P. 252 C.

The dye sensitized a silver chlorobromide emulsion to 660 Ill .0 with a peak at 600 m and a silver bromoiodide emulsion to 640 m with a peak at 590 m EXAMPLE 6.(3 ETHYL 2 BENZOTHIAZOLE)- [5-(3-DIMETHYLAMINOBUT 2 ENYLIDENE)- 3 ETHOXYCARBONYLMETHYL 4 THIAZOLI- DINONE1METHINCYANINE IODIDE EB S N This dye, prepared as Example 5 from the intermediate dye of Example 3, was obtained from ethanol-ether as bronze leaflets, M.P. 240 C. with decomposition.

It sensitized a silver chlorobromide emulsion to 660 mp. with a peak at 590 m and a silver bromoiodide emulsion to 640 mp with a peak at 590 mu.

EXAMPLE 7.-5 (3 DIMETHYLAMINOBUT-Z- ENYLIDENE) 3 ETHOXYCARBONYLMETH- YL-2-(3-ETHOXYCARBONYLMETHYL 4 0X0- 2 THIOTHIAZOLIDIN-S-YLIDENE)THIAZOLID- 4-ONE O 0 ll II N EXAMPLE 8.--2 (4 DIMETHYLAMINOPENTA- 1,3 DIENYL) 3 ETHYLBENZOTHIAZOLIUM PERCHLORATE sl 2 COH=CHCH= CH3 C1049 e i C2115 3-ethyl 2 methylbenzothiazolium iodide (1.5 g.), 1- anilino-3-dimethylimmonium-l-butene perchlorate (1.4 g.), acetic anhydride (0.5 ml.) and triethylamine 1.4 cc.) in ethanol 10 cc.) were refluxed together for 20 minutes, and chilled. The product was filtered 01f, washed with ethanol and recrystallized repeatedly from methanol to give cherry needles, M.P. 246 C.

In a similar fashion other dyes are prepared from N,N- dimethylisopro ylimmom'um perchlorate, 1-anilino-3-dimethylimmonium-l-butene perchlorate and l-acetanilido- S-dimethylimmonium-l-butene perchlorate according to the synthesis of my invention.

N,N-dimethylisopropylimmonium perchlorate This was prepared according to Malhotra, D. Phil. Thesis, Oxford 1958. Acetone (15.5 cc.) and dimethylamine perchlorate (27.5 g.) were mixed, warmed to dissolve, and kept at room temperature overnight. The product was filtered off and recrystallized from acetic acid as colorless needles, M.P. 285 C., in 30 g. yield.

Similarly the other compounds of Formula I are made by using the appropriate ketone in place of acetone in order to give a compound having the desired R and R groups.

1-anilino-3-dirnethylimmonium-Z-butene perchlorate e OQH5NH-CH=CHC=N(CH3)Q 0104 a N,N-dimethylisopropylimmonium perchlorate (1.85 g.) and ethylisoformanilide (1.55 g.) were heated together at for /2 hr. The mix was cooled, filtered, and then the product washed with ether, and recrystallized from methanol as orange crystals M.P. 230 C.

1-acetani1ido-3-dimethylimmonium-Z-butene perchlorate 1-anilino-B-dimethylimmonium-Z-butene perchlorate (1 g.) and acetic anhydride (8 cc.) were refluxed for 20 minutes. The cooled liquid was thrown into ether (40 cc.). The product which separated was heated several times with ether and recrystallized from methanol as pale cream leaflets, M.P. 158 C.

The synthesis of my invention is valuable for making sensitizing dyes of the styryl class, the hemicyanine class, the merocyanine class and certain complex dyes derived from the above dyes. These dyes are readily made by condensing N,N-dimethylisopropylimmonium perchlorate with intermediates, such as aromatic aldehydes, 2-alkylthio heterocyclic quaternary salts, alkoxymethylene derivatives of ketomethylene heterocyclic compounds, ethylisoformanilide, etc., or by condensing l-anilino or l-acetanilido-3-dimethylimmonium-Z-butene perchlorate with intermediates such as heterocyclic quaternary salts possessing reactive methyl groups, ketomethylene heterocyclic compounds, etc.

I claim:

1. A process for making dyes, said process comprising the step of heating a mixture of (l) a compound having the formula:

and (2) an intermediate selected from the group consisting of those having the formulas:

wherein R and R each represents a member selected from the group consisting of the hydrogen atom, an alkyl group having 1 to 5 carbon atoms, 2-chlorethyl, 2-cyanoethyl, 2-hydroxyethyl, benzyl, phenyl, chlorophenyl, methylphenyl and ethylphenyl; R represents a member selected from the group consisting of an alkyl group having 1 to 5 carbon atoms, allyl, ethoxycarbonylmethyl, flhydroxyethyl, B-acetoxyethyl and sulfobutyl; R represents a member selected from the group consisting of methyl, ethyl, phenyl, chlorophenyl and methylphenyl; Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of a thiazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a thinaphtheno-7',6,4,5-thiazole nucleus, an oxazole nucleus, a benzoxazole nucleus, at naphthoxazole nucleus, a selenazole nucleus, 3. benzoselenazole nucleus, a naphthoselenazole nucleus, at thiazoline nucleus, a 2-quinoline nucleus, a 4-quinoline nucleus, a l-isoquinoline nucleus, a 3-isoquinoline nucleus, a 3,3-dialkyl-3H- indole nucleus, a pyridine nucleus, a Z-pyridine nucleus, a 4-pyridine nucleus, an imidazole nucleus, a naphthimidazole nucleus and a benzimidazole nucleus; X represents an acid anion; W represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of a 2-pyraZolin-5-one nucleus, an isoxazolin-S-one nucleus, a Z-indolinone nucleus, a 2,4,6-triketohexahydropyrimidine nucleus, 21 rhodanine nucleus, a 2(3H)-imidazo[1,2-a]pyridone nucleus, a 5,7-dioxo-6,7- dihydro-S-thiazole[3,2-a1pyrimidine nucleus, at thianaphthenone nucleus, a 2-thio-2,5-thiazolidinedione nucleus, a 2,4-thiazolidinedione nucleus, a thiazolidinone nucleus, 21 4-thiazolinone nucleus, a 2-imino-2,4-oxazolinone nucleus and a S-imidazolinone nucleus; and R represents a member selected from the group consisting of an alkyl group having 1 to 5 carbon atoms, benzyl and allyl, in an inert organic solvent, in the presence of a basic condensing agent, said heating to raise the temperature of said mixture in the range from room temperature to the reflux temperature of said mixture.

2. A process for making 1-p-dimethylaminophenyl-3- dimethylimmonium-l-butene perchlorate comprising the step of heating a mixture of N,N-dimethylisopropylimmonium perchlorate and p-dimethylaminobenzaldehyde in ethanol, in the presence of piperidine, to reflux the said ethanol.

3. A process for making 2-(Z-dimethylaminopropenyl)- 3-ethylbenzothiazolium perchlorate comprising the step of heating N,N-dimethylisopropylimmonium perchlorate with 3-ethyl-Z-ethylthiobenzothiazolium p-toluenesulfonate in ethanol in the presence of triethylamine at the reflux temperature of the mixture.

4. A process for making 5-(3-dimethylaminobut-2- enylidene)-3-ethoxycarbonylmethylrhodanine comprising the step of heating N,N-dimethylisopropylimmonium perchlorate With 3-ethoxycarbonylmethyl-S-ethoxymethylene-rhodanine in ethanol in the presence of triethylamine at the reflux temperature of the mixture.

5. A process for making 5-(3-dimethylarninobut-2- enylidene)-3-ethylrhodanine comprising the step of heating 1-ar1ilino-3-dimethylimmonium-2-butene perchlorate With ethylrhodanine dissolved in ethanol in the presence of acetic anhydride and triethylamine at the reflux temperature of the mixture.

6. A process for making (3-ethyl-2-benzothiazole) [5- (3-dimethylaminobut 2 enylidene)-3-ethyl-4-thiazolidinone]rnethincyanine iodide comprising the steps:

(1) mixing l-anilino 3 dimethylimmonium-Z-butene perchlorate with ethylrhodanine dissolved in ethanol in the presence of acetic anhydide and triethylamine at the reflux temperature of the mixture.

(2) separating the dye 5-(3dimethylaminobut-2-enylidene)-3-ethylrhodanine formed in step 1 by filtering it from the chilled reaction mixture from step 1,

(3) fusing the said dye separated in step 2 with methyl p-toluene sulfonate, and

(4) mixing the product of step 3 With 3-ethyl-2-methylbenzothiazoliurn iodide in ethanol in the presence of triethylamine at the the reflux temperature of the mixture.

7. The dye l-p-dimethylaminophenyl 3 dimethylimmonium-l-butene perchlorate.

8. The dye 2,2-dimethylaminopropenyl 3 ethylbenzothiazolium perchloroate.

9. The dye 5-(3-dimethylaminobut 2 enylidene)-3- ethoxycarbonylmethylrhodanine.

10. The dye 5-(3-dimethylarninobut 2 enylidene)-3- ethylrhodanine.

11. The dye (3-ethyl-2-benzothiazole)[5-(3-dimethy1- aminobut-2-enylidene) 3 ethyl-4-thiazolidinone]methincyanine iodide.

References Cited UNITED STATES PATENTS 2,895,955 7/ 1959 Haseltine et al. 260-2405 2,984,664 5/1961 Fry et a1. 260-2405 2,304,981 12/1942 Wilmanns 96-106 2,870,014 1/1959 Brooker et a1. 96-106 2,131,865 10/1938 Zeh 260-2408 3,288,784 11/1966 Speziale et al. 260-566 OTHER REFERENCES Patrick, I. Am. Chem. Soc., vol. 74, p. 2984 (1952).

JOHN D. RANDOLPH, Primary Examiner US. Cl. X.R. 

